: The proposed research is a systematic examination of cancer risk in relation to family history of cancer in a large population-based genealogy. It is clear from numerous epidemiologic and genetic studies that a family history of many kinds of cancer increases a person's risk of cancer, and in several cases mutations of particular genes have been identified that are associated with familial cancer syndromes. However, for the vast majority of cancers, the specific contributions of inherited predisposition to cancer risk have not been well described. We propose to examine cancer risk associated with family histories of cancer in a large cohort of people identified through the Utah Population Database (UPDB), a resource that contains pedigree information up to six generations deep on over one million individuals. The genealogy records are linked on a continuing basis to the records of the Utah Cancer Registry, which has recorded all cancers diagnosed in Utah since 1966. We will examine alternative methods for estimating familial aggregation of cancer, estimate relative and attributable risks associated with family history for 36 different kinds of cancer, and examine the patterns of familial coaggregation of cancer. In order to accomplish these goals, we will incorporate new follow-up information into UPDB that we will make available to all users of the database.